The use of complexing agents which combine with metal ions in solution to form soluble complexes (which agents are commonly referred to as sequestrants) is of great importance in many industrial processes inasmuch as it may prevent undesired precipitation reactions from occurring. For example, sequestration of calcium is important in water treatment and in laundry solutions for controlling hardness of the water. Sequestration of the heavy metals such as copper and nickel is essential in such areas as textile processing, metal cleaning and finishing. Not all sequestrants, however, are equally effective, their activity varying with their structures and the conditions under which they are used, for example, the common carboxylic acid sequestrants are often ineffective in preventing ferric ion precipitation from alkaline solutions of pH greater than 8.
The commercial utilization of water-soluble chelating compounds in agricultural applications to provide trace elements for plant growth is well known. Likewise, the treatment of plants suffering from chlorosis as a result of growth in alkaline soils devoid of sufficient assimilatable iron is known. Various chelating agents have been employed in the past to correct iron deficiencies in plants, the water solubility of chelated metal ions affords a primary route for potential assimilation into a plant structure.
Ethylenediaminetetraacetic acid (EDTA) has been employed in the past for treatment of iron deficiencies of citrus trees under acid conditions. The EDTA iron chelates are not stable in neutral and alkaline media. The development of sequestrants which may be employed in acid media as well as alkaline media is significant not only for agricultural applications, but for use in the detergent field, metal cleaning field, textile and dye industry and as stabilizers for organic and inorganic peroxides.
The use of sequestrants in sulfite baths for the electrodeposition of gold and gold alloys as additives for improving the performances and the operating conditions of said baths is also of high importance. In general, additives which will strongly limit, during electrolysis, the influence on the quality of the deposits of the variations of some operating factors, such as temperature, pH of the bath, current density, type and degree of agitation, etc., are desirable. It is well known in the art of electrodepositing gold and gold alloys from sulfite baths that the above operating factors normally have a strong influence on the nature and the properties of the coatings obtained. Thus, it is often necessary to accurately control some of said factors in order to obtain deposits having the properties required (color, ductility, gloss, etc.). Most often, relatively slight variations of current density result in the formation of foggy deposits, burns, pittings or color changes, particularly when depositing gold alloys. The introduction of the instant compounds into sulfite gold baths largely prevents these difficulties. In the presence of such additives, it is possible to vary operational factors between relatively wide limits without affecting the quality of the coatings and, in the case of gold alloys, without appreciably modifying the composition and the carat thereof. The principle of action of these additives is not known exactly; it is, however, possible that they may standardize the electrochemical properties of the various metals which are plated simultaneously, e.g., the electrodeposition potential and the distribution of ions in the cathode layer.
Further, many flame retarding agents and methods of application have been developed in attempts to obtain flame resistant textile materials and thermoplastic resin compositions.
Flame retardant textiles have been produced by depositing metal oxides, within or on the textile fibers, by the successive precipitation of ferric oxides and a mixture of tungstic acid and stannic oxide or by successive deposition of antimony trioxide and titanium dioxide. Such processes require plural treatment baths in which strongly acidic solutions are employed, thus posing the problem of possible textile degradation. Furthermore, metal oxide coatings on textile materials create difficulties in subsequent dyeing processes which deleteriously affect the hand of the finished product. Other processes involve the use of a single processing bath wherein a dispersion of chlorinated hydrocarbon and finely divided antimomy oxide is padded on the textile material. Near the textile combustion temperature, antimony oxide will react with hydrogen chloride, generated by degradation of the chlorinated hydrocarbon, to form antimony oxychloride which acts to suppress flame. This combination of a chlorinated hydrocarbon and finely divided antimony oxide are not acceptable finishes for closely woven textiles as they deleteriously affect the hand of the finished product. A further process for imparting flame resistance to cellulosic materials is by the esterification of the cellulose with diammonium hydrogen ortho-phosphate. Textile products so treated, however, are subject to metathesis reaction with cations during washing, and must be regenerated by reacting the wash product with an ammonium chloride solution.
The production of thermoplastic resin compositions which are flame retardant is of considerable commercial importance. For example, such articles as castings, moldings, foamed or laminated structures and the like are required, or are at least desired, to be resistant to fire and flame and to possess the ability to endure heat without deterioration. The use of various meterials incorporated into thermoplastic resins so as to improve the flame retardancy thereof has been known. Many compounds have been commercially available for such use, among them being chlorostyrene copolymers, chlorinated paraffin wax in admixture with triphenyl styrene, chlorinated paraffins and aliphatic anatimonical compounds, as well as antimony oxide-chlorinated hydrocarbon mixtures. A problem associated with these compounds has been, however, the fact that generally a large amount, i.e. upwards to 35% of additive, must be incorporated into the resin in order to make it sufficiently flame retardant. Such large amounts of additive may deleteriously affect the physical characteristics of the thermoplastic resin, as well as substantially complicating and increasing the cost of preparation thereof. A further problem is that these prior art additives tend to crystallize or oil out of the resin after a relatively short time of incorporation. The present invention relates to a group of compounds which may be added to thermoplastic resins in relatively small amounts and still produce satisfactory flame retardant compositions which will not crystallize nor oil out of the resin after incorporation therein.